Crawler moving mechanisms are commonly used in devices, such as in wheelchairs or toys for driving them to move on the road. Such conventional moving mechanisms can only move on smooth paved roads and being powerless to move on complex non-paved roads with various road conditions due to their own design features. For example, such conventional moving mechanisms do not function properly or might occasionally bring about danger to users when operating on rugged uneven roads or obstacles of various height, or going up and down ramps or even stairs of various slopes.
As shown in FIG. 1a, the crawler moving mechanism 1000, comprising the crawler/caterpillar/track 1100 and the wheel 1200, might fail to climb up and be stuck in the midway or have a danger of sudden fall, when climbing stairs of various slopes;
as illustrated in FIG. 1b, when reaching the top of the stairway, there might be a danger of sudden fall; and
as illustrated in FIG. 1c, though the crawler moving mechanism 1000 has the tank-like crawler assembly 1100 and 1200 and can move on rough terrain and climb over obstacles, but it has a drawback as a tank does, namely it has also a danger of sudden fall when crossing a protrusion. When the crawler moving mechanism moves on an even running surface, and each time it turns, crawlers at both sides will press closely against the surface, so the turning is extremely unsmooth and uneasy, and the crawler might also cause damage to the surface as it will scratch the surface badly during turning.
To this end, those skilled in the art have proposed also a number of solutions. For example, CN103027803 A has disclosed an electric vehicle comprising a movable seat part, a body part served as a support for the seat part, a seat adjustment mechanism arranged under the seat part, a bottom part, and a crawler moving mechanism. The crawler moving mechanism comprises two sets of crawlers arranged respectively at both sides underneath the bottom part, and each of which comprises a front crawler and a rear crawler. The bottom part is comprised of a front portion and a rear portion, which are movably connected with a coupling arrangement and capable of deflection with respect to each other. The crawler moving mechanism further comprises movable stretching crawlers arranged respectively at outside of the front crawler, and fixed stair-climbing crawlers arranged respectively at outside of the rear crawler, wherein a free end of the fixed stair-climbing crawler forms a specific angle relative to the rear crawler. It makes use of several crawler moving mechanisms and a balance device to realize the moving over the non-paved road, and it has produced certain technical effects, but it is relatively bulky and costly per se.
Obviously, the foregoing designs have posed heavy limits to application and development of those wheelchairs or toys. Therefore, it is necessary to design a new moving mechanism, which has not only the capabilities of the traditional moving mechanisms, but also the capabilities of climbing stairs of various slopes, moving easily on rugged roads, crossing various obstacles without causing danger, and the like.